All-optical helicity dependent magnetic switching in Tb-Fe thin films with a MHz laser oscillator

We demonstrate all-optical magnetic switching (AOS) in an amorphous Tb30Fe70 thin film, triggered by a 5.1 MHz laser oscillator. The magnetic layer is grown on a SiO2/Si substrate. An identical magnetic film deposited on a microscope glass slide shows no AOS and only exhibits thermally induced demagnetization. This effect is due to heat accumulation by multiple laser pulses because of the low thermal conductivity of the glass substrate. In contrast, the use of a proper heat sink (e.g. SiO2/Si) abolishes need for low repetitive laser amplifier systems to induce AOS and paves the way for a cheap and easy to use technological implementation with conventional laser oscillators.